Poly-based burr suppressor

ABSTRACT

A burr-suppressing copper foil is described. In an embodiment, the burr-supressing copper foil includes a poly-based film having an adhesive on a first side and an adhesive on a second side. A copper foil contacts the adhesive at the first side of the poly-based film to removably couple the poly-based film to the copper foil. A metallic burr suppressor contacts the adhesive on the second side to removably couple the poly-based film to the metallic burr suppressor.

RELATED APPLICATION

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 15/266,267 filed on Sep. 15, 2016, the contents ofwhich is incorporated by reference.

TECHNICAL FIELD

The present application relates to circuit boards and, moreparticularly, to materials and methods for suppressing burrs duringmanufacture of circuit boards.

BACKGROUND

During printed circuit board (PCB) manufacture, holes are typicallydrilled into the PCB. These holes may be used for the insertion ofthrough-hole-component leads or may be used as “vias” to connect boardlayers.

The PCB has an exposed copper surface. Since copper is a very softmetal, the copper tends to burr if it is drilled without adequatesupport. Current methods of avoiding or suppressing burrs during the PCBdrilling process involve stacking the PCB on a backup material,typically constructed of Melamine or hard-coated high-density fiberboard(HDF). The top side of the PCB is covered with an aluminum entry, whichis often a sheet of aluminum approximately 150 microns to 250 microns inthickness. This technique has many drawbacks. For example, in someinstances, while an operator is placing the PCB on the backup materialor placing the aluminum entry material on top of the PCB, debris maybecome trapped between the PCB and either the backup material or thealuminum entry material. This debris may create a gap between the PCBand the backup material or aluminum entry material and the gap may allowa burr to be formed.

Gaps between the PCB and the backup material or the aluminum entrymaterial may also exist if the PCB is not perfectly flat. For example, awarped PCB may create such gaps, allowing burrs to form during drilling.

In some instances, burrs may be pushed back into their associated holeso that the burr height of the burr (i.e., the amount by which the burrextends over the PCB) is reduced or eliminated. However, pushing theburr back into the hole can result in an undersized hole. This can causea PCB to be rejected, resulting in scrapping of the PCB.

Furthermore, the back-up material that is commonly used for burrsuppression is a coated wood core back-up material which is relativelyexpensive.

Thus, there is a need for improved methods and materials for suppressingburrs during PCB manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made, by way of example, to the accompanyingdrawings which show embodiments of the present application, and inwhich:

FIG. 1 is a perspective view of a burr suppressing copper foil;

FIG. 2 is a side view of the burr suppressing copper foil of FIG. 1;

FIG. 3 is a side view of an example lamination press arrangement;

FIG. 4 is a side view of an example book for use in the lamination pressarrangement of FIG. 3;

FIG. 5 is a flowchart of an example method of manufacturing a printedcircuit board;

FIG. 6 is a side view of an example book on an uncoated wood corematerial;

FIG. 7 is a block diagram of an example machine for manufacturing a burrsuppressing copper foil; and

FIG. 8 is a flowchart of an example method of manufacturing a burrsuppressing copper foil.

Like reference numerals are used in the drawings to denote like elementsand features.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

As will be described in greater detail below, in some embodiments aburr-suppressing copper foil is described. In an embodiment, the burrsuppressing copper foil includes a poly-based film having an adhesive ona first side and an adhesive on a second side. A copper foil contactsthe adhesive at the first side of the poly-based film to removablycouple the poly-based film to the copper foil. A metallic burrsuppressor contacts the adhesive on the second side to removably couplethe poly-based film to the metallic burr suppressor.

In another aspect, a method of manufacturing a burr-suppressing copperfoil is described. The method comprises: providing a copper foil, ametallic burr suppressor, and a poly-based film, the poly-based filmhaving an adhesive applied to opposing sides of the poly-based film;attaching the copper foil to the poly-based film at a first side of thepoly-based film using the adhesive; and attaching the metallic burrsuppressor at a second side of the poly-based film using the adhesive.

In yet another aspect, a method for manufacturing a printed circuitboard (PCB) is described. The method includes: constructing a bookhaving a burr-suppressing copper foil on at least one exterior sides ofthe book, the burr-suppressing copper foil comprising a poly-based filmhaving an adhesive applied at opposing sides, a copper foil coupled tothe poly-based film on a first side of the poly-based film and ametallic burr suppressor coupled to the poly-based film on a second sideof the poly-based film, the metallic burr suppressor being an outerlayer of the book; applying a lamination cycle to the book using alaminating press to cure the book; and after the lamination cycle,drilling the laminated book.

Reference will first be made to FIGS. 1 and 2 which illustrate anexample burr-suppressing copper foil 100. FIG. 1 illustrates aperspective view of the burr-suppressing copper foil 100 while FIG. 2illustrates a side view of the burr-suppressing copper foil 100.

The burr-suppressing copper foil 100 includes a copper foil 102. Thecopper foil 102 may have a thickness in the range of 9 to 70 microns. Insome embodiments, the copper foil may be thinner, having a thicknessthat is less than 9 microns.

In order to provide burr-suppressing features to the copper foil 102which will help prevent burrs during drilling, the copper foil 102 maybe removably attached to a metallic burr suppressor 103 with an adhesive104.

For example, in the example illustrated, the copper foil 102 isremovably attached to the metallic burr suppressor 103 with a poly-basedfilm 106. The poly-based film 106 has an adhesive 104 applied at bothsides so that side of the poly-based film 106 has sticky surfaces. Thisallows the poly-based film 106 to stick to both the copper foil 102 andthe metallic burr suppressor 103 when the adhesive of the poly-basedfilm is brought into contact with the copper foil 102 and the metallicburr suppressor 103.

Accordingly, an adhesive 104 is provided between the poly-based film 106and the copper foil 102 and also between the poly-based film 106 and themetallic burr suppressor 103. The adhesive 104 is permanently attachedto the poly-based film and is removably attached to the copper foil 102.Thus, when the poly-based film 106 is detached from the copper foil 102,the adhesive remains on the poly-based film 106 and not the copper foil102.

The adhesive 104 that is applied to the poly-based film 106 may alsoremovably attach the metallic burr suppressor 103 to the poly-based film106 to facilitate recycling of the metallic burr suppressor 103. Forexample, after drilling of a PCB, the poly-based film 106 may be removedfrom the PCB by detaching the poly-based film 106 from the copper foil102 (which forms an outer layer of the PCB). The poly-based film 106 mayalso be detached from the metallic burr suppressor 103 so that themetallic burr suppressor 103 can be recycled.

The metallic burr suppressor 103 and the copper foil 102 are coupled tothe poly-based film at opposing sides of the poly-based film such thatthe poly-based film 106 is sandwiched between the metallic burrsuppressor 103 and the copper foil 102. For example, the copper foil 102may be attached at a first side and the metallic burr suppressor 103 maybe attached at a second side which is opposite the first side.

The metallic burr suppressor 103 is a non-ferrous metal. For example, inone embodiment, the metallic burr suppressor 103 is a copper layer, suchas a copper panel. In another embodiment, the metallic burr suppressor103 is an aluminum layer such as an aluminum panel. In some embodiments,different versions of the burr-suppressing copper foil may beconstructed for suppressing burrs in different environments. Forexample, in some embodiments, an aluminum version (i.e., a version inwhich the metallic burr suppressor is aluminum) may be used forsuppressing a burr at an entry side of a drill while a copper version(i.e., a version in which the metallic burr suppressor is copper) may beused for suppressing a burr at an exit side of a drill. The entry sideis the side of the PCB at which the drill first enters the PCB and theexit side is the side at which the drill exits the PCB. In oneembodiment of the aluminum version of the burr-suppressing copper foil,the aluminum metallic burr suppressor is between 150 to 250 micronsthick. In one embodiment of the copper version of the burr-suppressingcopper foil, the copper metallic burr suppressor is between 17 and 70microns thick.

Turning now to a discussion of the copper foil 102, the copper foil isthe portion of the burr-suppressing copper foil 100 which will be usedin a PCB. The poly-based film and the metallic burr suppressor 103 areremoved from the PCB after drilling, but the copper foil 102 itself willremain as an outer layer of the PCB.

Since the poly-based film 106 and the metallic burr suppressor 103 areonly removed after drilling, they will typically remain attached to thecopper foil 102 during a lamination process in which the copper foil 102is laminated to other layers of a PCB. During this lamination process,the burr-suppressing copper foil 100 may be subjected to temperatures inexcess of 180 degrees Celsius or greater in order to cure prepreg andlaminate the PCB. The specific temperatures that are required willdepend on the nature of the prepreg used, but in some instances thetemperatures may even exceed 200 degrees Celsius.

Notably, many poly-based films cannot be heated to such temperatures andwould deteriorate under such conditions. Due to the sensitive nature ofPCB manufacturing any deterioration that could leave residue on the PCBafter manufacture could result in adverse effects, such as anon-functioning PCB.

The poly-based film 106 may be a polyethylene terephthalate (PET) film.Notably, while many poly-based films operate poorly in high-temperatureenvironments, the PET film operates well in such environments. The PETfilm does not deteriorate under a heating temperature of one 180 degreesCelsius and does not deteriorate at heating temperatures of 200 degreesCelsius.

In some embodiments, the poly-based film 106 may be an Ethylenetetrafluoroethylene (ETFE) film. ETFE film also has a high temperatureresistance and has been found to perform well in the temperature rangeof intended applications.

The thickness of the poly-based film 106 may vary but in someembodiments, the poly-based film 106 has a thickness of between 45 and100 microns.

Since the poly-based film 106 remains attached to the copper foil 102throughout much of the manufacturing process of the PCB, the poly-basedfilm 106 (and the metallic burr suppressor 103) acts as a protector,protecting the copper foil 102 from damage, dirt and debris.Accordingly, the poly-based film 106 may be referred to as a protectivefilm.

The adhesive 104 used to removably couple the poly-based film 106 to thecopper foil 102 is a low-tack adhesive that allows the copper foil 102to be easily removed from the poly-based film 106 and the adhesive 104(i.e., it can be removed by a human without mechanical assistance). Forexample, the adhesive may have a tack/adhesion strength less than orequal to 6 grams per 25 millimeter width. In some embodiments, thetack/adhesion strength is between 3 to 6 grams per 25 millimeter width.

The tack strengths referred to above refer to the tack strength that theadhesive has with the copper foil 102 (and the metallic burr suppressor103). The adhesive 104 adheres to the poly-based film 106 with a muchgreater force. For example, the adhesive may be permanently applied tothe poly-based film 106. Thus, when the poly-based film 106 is separatedfrom the copper foil 102 and the metallic burr suppressor 103, theadhesive 104 remains on the poly-based film 106 and not the copper foil102 or the metallic burr suppressor 103.

In some embodiments, the adhesive 104 used to attach the poly-based film106 to the metallic burr suppressor 103 may be the same as the adhesiveused to attach the poly-based film 106 to the copper foil 102. In otherembodiments, however, these adhesives may be different to facilitateseparation. For example, in one embodiment, the adhesive may beconfigured or selected so that the tack strength between the metallicburr suppressor 103 and the poly-based film 106 is greater than the tackstrength between the copper foil 102 and the poly-based film 106. Inthis way, the poly-based film 106 and the metallic burr suppressor 103may be easily removed from the copper foil as a single unit and then thepoly-based film 106 can subsequently be detached from the metallic burrsuppressor 103.

In at least some embodiments, the adhesive 104 is a non-silicone basedadhesive. Since silicone is a semi-conductor, the use of a siliconeadhesive can cause defects in PCBs if any silicone residue is left onthe copper foil 102 when the poly-based film 106 is detached from thecopper foil 102.

The adhesive 104 may be an acrylic adhesive. Acrylic adhesives have goodtemperature performance That is, the acrylic adhesive 104 does notdegrade under the high temperatures that some applications of theproduct require. For example, the acrylic adhesive, in at least someembodiments, does not degrade at a temperature of 180 degrees Celsius.In at least some embodiments, the acrylic adhesive does not degrade at atemperature of 200 degrees Celsius. “Degrade”, as used herein withrespect to the adhesive, means to break down in quality or consistencyso as to leave behind adhesive residue on the copper foil when thecopper foil and the poly-based film are detached from one another. Thatis, the adhesive is considered not to have degraded if it continues toremove well from the copper foil.

The adhesive 104 is uniform across a surface of the poly-based film 106that contacts the copper foil 102. That is, the adhesive 104 resides atall locations between the poly-based film 106 and the copper foil 102and is applied at approximately the same coat weight irrespective of itslocation on the surfaces. For example, in at least some embodiments, theadhesive may be approximately 25 to 50 microns in thickness. Thethickness of the adhesive may be the same across the entire surface ofthe poly-based film 106 that contacts the copper foil 102. Applying theadhesive across the entire surfaces of the copper foil 102 and thepoly-based film 106 aids in preventing the poly-based film fromdetaching from the copper foil 102 during drilling.

The adhesive 104 is also uniform across a surface of the poly-based film106 that contacts the metallic burr suppressor 103. That is, theadhesive 104 resides at all locations between the poly-based film 106and the metallic burr suppressor 103 and is applied at approximately thesame coat weight irrespective of its location on the surfaces. Forexample, in at least some embodiments, the adhesive may be approximately25 to 50 microns in thickness. The thickness of the adhesive may be thesame across the entire surface of the poly-based film 106 that contactsthe metallic burr suppressor 103. Applying the adhesive across theentire surfaces of the copper foil 102 and the poly-based film 106 aidsin preventing the poly-based film from detaching from the copper foil102 during drilling.

Reference will now be made to FIG. 3, which illustrates an examplelamination press arrangement 300 for one application of theburr-suppressing copper foil 100 of FIGS. 1 and 2.

The lamination press arrangement 300 of FIG. 3 includes a laminationpress 302 used to manufacture a PCB. More particularly, in the examplethe lamination press 302 is used to manufacture a multi-layer PCB. Thelamination press 302 is a specialized hydraulic press with heatedplatens 303. The heated platens 303 are used to cure prepreg. A prepreg(or pre-impregnated layer) is fiberglass that is impregnated with aresin (i.e., a thermosetting epoxy). The resin is dried but not hardenedsuch that it flows when heated, by the lamination press 302, to a curingtemperature.

The lamination press is configured to apply heat and pressure to layerswhich form the PCB to bond them together.

The lamination press 302 includes caul plates 304. The caul plates 304include both an upper and a lower caul plate. The caul plates 304 (whichmay also be referred to as carrier plates or tooling plates) rest in thelamination press 302. More particularly, the caul plates 304 areadjacent the heated platens 303.

In at least some embodiments, padding 306 may be inserted between thecaul plates 304 and the layers that will form the PCB. That is, theremay be upper and lower padding 306, bounding the layers that will formthe PCB. This padding 306 is used to control the rate of heat transferbetween the heated platens 303 and the layers that will form the PCB.Further, the padding 306 can be used to compensate for imperfectionssuch as non-parallel, bowed or warped platens, imperfections in the caulplates, etc. In some embodiments, the padding 306 may include severalplies of thick Kraft paper. In some embodiments, the padding 306 mayinclude press pad.

One or more books 310 are provided between the caul plates 304 andbetween the padding 306. In the example of FIG. 3, two books 310 areillustrated. However, a greater or lesser number of books may beinserted within the lamination press at any given time. For example, insome embodiments, only a single book is included. In other embodiments,a greater number of books are included. By way of example, in oneembodiment, six books may be included in the lamination press at a giventime.

The books 310 may be separated from one another by a separator plate312. The separator plate 312 is a hard metal plate, such as stainlesssteel (in which case the separator plate may be referred to as astainless steel separator plate).

Reference will now be made to FIG. 4 which illustrates an example book310. The example book 310 includes two burr-suppressing copper foils100. The burr-suppressing copper foils 100 are of the type describedabove with reference to FIGS. 1 and 2. A first one of theburr-suppressing copper foils 100 is located at the bottom of the book310 and a second one of the burr-suppressing copper foils 100 is locatedat the top of the book 310. The metallic burr suppressors 103 of theburr-suppressing copper foils 100 are outward facing. That is, themetallic burr suppressors are the outside layer of the book 310.Notably, the poly-based films 106 helps to provide some padding, muchlike the padding 306 discussed above. The padding provided by thepoly-based films 106 can help reduce the transmission of imperfectionsfrom the separator plates 312 or the caul plates 304 to the copper foil102.

In at least some embodiments, the book 310 may include a differentversion of the burr-suppressing copper foil 100 on the top side than onthe bottom side of the book 310. For example, in one embodiment, analuminum version of the burr-suppressing copper foil 100, in which themetallic burr suppressor is an aluminum layer, is located on the topside, while a copper version of the burr-suppressing copper foil 100, inwhich the metallic burr suppressor is a copper layer, is located on thebottom side. Thus, one end on the book is a drill-entry end, which hasthe aluminum version of the burr-suppressing copper foil 100 while theother end of the book is a drill-exiting end, which has the copperversion of the burr-suppressing copper foil 100.

The copper foils 102 of the burr-suppressing copper foils 100 areadjacent to and in contact with prepreg 402. For example, a firstprepreg 402 is adjacent the copper foil 102 associated with the bottomone of the burr-suppressing copper foils 100 and a second prepreg 402 isadjacent the copper foil 102 associated with the top one of theburr-suppressing copper foils 100.

Between the first and second prepreg is one or more copper cladlaminates (CCL) 404. That is, a first prepreg may be adjacent the copperfoil of a first burr-suppressing copper foil 100 and also adjacent theCCL 404 and a second prepreg may be located at a side of the CCL thatopposes the side adjacent the first prepreg.

The copper clad laminate (CCL) may be a two-sided CCL 404. In theexample, only a single CCL 404 is included to form a four-layer PCB.However, in practice there may be a greater number of CCLs included.Each CCL layer is separated from adjacent CCL layers with prepreg.

Referring now to FIG. 5, a method 500 of manufacturing a PCB will bedescribed. The method 500 makes use of a burr-suppressing copper foil100 of the type described above with reference to FIGS. 1 to 2 and alamination press 302 of the type described above with reference to FIG.3.

The method includes, at operation 502, constructing one or more books310 of the type described above with reference to FIG. 4. The books aregenerally constructed in a bottom-up fashion, beginning at the lowestlayer in the stack-up and proceeding to the top layer. By way ofexample, a first book 310 may constructed by stacking a bottomburr-suppressing copper foil 100 with the metallic burr suppressor 103downwardly facing and the copper foil 102 upwardly facing and thenadding a layer of prepreg 402 on top of the copper foil 102. The bottomburr-suppressing copper foil 100 may be the copper version of theburr-suppressing copper foil.

A CCL 404 may then be added to the prepreg 402 and additional CCLs maybe added, if desired, along with respective prepreg layers. Then,prepreg 402 is stacked on top of the uppermost CCL 404 and anotherburr-suppressing copper foil 100 is added to that prepreg 402. Thisupper burr-suppressing copper foil 100 is oriented so that the copperfoil 102 faces downward and is in contact with the prepreg 402 and sothat the metallic burr suppressor 103 faces upward. The upperburr-suppressing copper foil 100 may be the aluminum version of theburr-suppressing copper foil.

Accordingly, a book is constructed in 502 which has a burr-suppressingcopper foil on at least one exterior side of the book and, in someembodiments, on both exterior sides. The burr-suppressing copper foil100 is as described above with reference to FIGS. 1 and 2. For example,the burr-suppressing copper foil 100 includes a poly-based film havingan adhesive applied at opposing sides, a copper foil coupled to thepoly-based film on a first side of the poly-based film and a metallicburr suppressor coupled to the poly-based film on a second side of thepoly-based film. The metallic burr suppressor is, therefore, an outerlayer of the book.

If multiple books are to be included in one lamination cycle, aseparator plate 312 may be applied on a first side of the constructedbook. More particularly, the separator plate 312 may be applied on topof the upper metallic burr suppressor 103 so that a further book may bestacked on top. This process may be repeated until the desired number ofbooks are constructed.

At operation 504, a lamination cycle is applied to the book(s) using alamination press 302 of the type described above with reference to FIG.3 to cure the prepreg 402. The lamination is performed using specificpredetermined operating characteristics, include specific times,temperatures and pressures. These characteristics depend, at least inpart, on the prepreg that is used. The lamination cycle may heat thebook(s) to at least 180 degrees Celsius, in some embodiments. In someembodiments, the lamination cycle may heat the book(s) to at least 200degrees Celsius. The lamination cycle may, in some embodiments, takebetween 60 and 100 minutes. However, other lamination cycles may be usedin other embodiments.

After the lamination cycle, de-booking occurs. In some embodiments, thebook(s) may be subjected to a cooling cycle prior to de-booking. Forexample, cold water may be run over the book(s) to quickly cool them andan operator can then de-book.

At operation 505, the laminated book is drilled. In at least someembodiments in which the book includes different versions of theburr-suppressing copper foil 100 at an upper end of the book than at alower end of the book, the drilling occurs so that the drill enters analuminum version of the burr-suppressing copper foil 100 and exits acopper version of the burr-suppressing copper foil 100. For example, analuminum panel may form an entry side of the book for a drill bit whilea copper panel may form an exist side of the book for the drill bit.

Referring briefly to FIG. 6, in at least some embodiments, prior todrilling, the laminated book 310 is placed on an uncoated wood corematerial 550, such as Tek-Board (i.e., such that the bottomburr-suppressing copper foil 100 contacts the uncoated wood corematerial). Such materials are cheaper than the coated word core materialthat is used during traditional drilling processes.

Referring again to FIG. 5, at operation 506, the poly-based films 106are removed from the book(s). That is, the poly-based films 106 areremoved from respective copper foils. Notably, when this occurs, thereis no banding of the adhesive; the acrylic adhesive removes cleanly anddoes not remain on the copper foil 102 after removal of the poly-basedfilm 106.

After the poly-based film is removed to expose the copper foil 102, thecopper foil 102 may be etched.

The poly-based films may also be detached from the metallic burrsuppressors so that the metallic burr suppressors may be recycled.

Techniques for manufacturing the burr-suppressing copper foil 100described above will now be discussed. Reference will first be made toFIG. 7, which illustrates, in block form, a sample machine 600 formanufacturing a burr-suppressing copper foil 100. The machine 600 may belocated in a clean room environment, in some embodiments.

The machine includes a first material handling unit 602. The firstmaterial handling unit 602 receives the copper foil 102 of the typedescribed herein with reference to FIGS. 1 and 2. The copper foil 102may be received in roll form. In at least some embodiments, the materialhandling unit allows the roll to rotate.

The machine 600 also includes a second material handling unit. 604. Thesecond material handling unit 604 is for receiving a poly-based film 106of the type described above with reference to FIGS. 1 and 2. In at leastsome embodiments, the poly-based film 106 has an adhesive applied toboth surfaces of the poly-based film 106. That is, a first side and asecond side of the poly-based film may both have an adhesive 104 of thetype described herein applied thereon. In at least some embodiments, aliner, such as a mylar liner, may act as a backing to the adhesive andthe second material handling unit 604 may be configured to remove theliner. The poly-based film may be received in roll form. In at leastsome embodiments, the material handling unit allows the roll to rotate.

The machine 600 also includes a third material handling unit 621. Thethird material handling unit 621 is for receiving a metallic burrsuppressor 103 of the type described herein with reference to FIGS. 1and 2. The metallic burr suppressor 103 may be received in roll form. Inat least some embodiments, the material handling unit 621 allows theroll to rotate.

At least one roller 607 (or other material gripper) is provided in themachine, and, at least one of the rollers (or another material gripper)is coupled with a drive. The drive rotates the roller 607 (or otherwisedrives the material gripper) causing the roller 607 to pull the copperfoil and the metallic burr suppressor into contact with the poly-basedfilm and to attach the copper foil and the metallic burr suppressor tothe poly-based film using the adhesive applied to the surfaces of thepoly-based film.

The at least one roller 607 may be configured to remove any air bubblesbetween the poly-based film 106 and the copper foil 102 and between thepoly-based film 106 and the metallic burr suppressor 103 and may, in atleast some embodiments, be configured to apply a force to the poly-basedfilm 106 to hold the poly-based film taut during the attaching.

The machine 600 may also include a cleaner 606 for cleaning thepoly-based film prior to the attaching. The cleaner 606 may include oneor more adhesive take-up rollers which have a tack for removing debris.In some embodiments, the adhesive take-up rollers may include siliconerollers.

The machine 600 may also include a cleaner 608 for cleaning the copperfoil 102 prior to the attaching. Such cleaners 608 may include one ormore adhesive take-up rollers which have a tack for removing debris. Insome embodiments, the adhesive take-up rollers may include siliconerollers.

The machine 600 may also include a cleaner 619 for cleaning the metallicburr suppressor 103 prior to the attaching. Such cleaners 608 mayinclude one or more adhesive take-up rollers which have a tack forremoving debris. In some embodiments, the adhesive take-up rollers mayinclude silicone rollers.

The machine 600 may also include a punching station 612 which addstooling holes for receipt in the lamination press 302. The punchingstation is located so that holes are applied after the copper foil andthe metallic burr suppressor have been attached to the poly-based film.

The machine 600 may also include a shearing station 614. The shearingstation 614 cuts the burr-suppressing copper foil 100 into panels thatfit within the lamination press 302. For example, in one embodiment, theburr-suppressing copper foil 100 is cut into 18″×24″ panels.

In some embodiments, the machine 600 may not include the shearingstation 614 and/or the punching station. If desired, such panelizing andtooling operations could be done offline. That is, the machine 600 maymanufacture a roll of burr-suppressing copper foil 100 and, if desiredfor a particular application, the roll could be post-processed toinclude tooling features and to cut the roll into smaller portions.

Reference will now be made to FIG. 8, which illustrates a flowchart of amethod 800 for manufacturing a burr-suppressing copper foil 100 of thetype described above with reference to FIGS. 1 to 2. The method 800 maybe performed in a clean room environment.

At operation 802, the method 800 includes providing a copper foil 102 ofthe type described with reference to FIGS. 1 and 2, a metallic burrsuppressor of the type described with reference to FIGS. 1 and 2, and apoly-based film 106 of the type described with reference to FIGS. 1 and2. The poly-based film has an adhesive of the type described withreference to FIGS. 1 and 2 applied to opposing sides of the poly-basedfilm (i.e, it has a double-sided adhesive coating).

In at least some embodiments, at operation 804, the poly-based film 106and/or the copper foil 102 and/or the metallic burr suppressor 103 arecleaned. Such cleaning may be performed by passing the material over oneor more adhesive take-up rollers that have a tack for removing debris.These take-up rollers may be, for example, silicone rollers.

At operation 806, the copper foil 102 is attached to the poly-based filmat a first side of the poly-based film using the adhesive applied to thesurface of the poly-based film. For example, the copper foil 102 and thepoly-based film 106 may be pressed into contact. The poly-based film maybe held taut during the attaching.

At operation 806, the metallic burr suppressor 103 is attached to thepoly-based film at a second side of the poly-based film using theadhesive applied to the surface of the poly-based film. For example, themetallic burr suppressor 103 and the poly-based film 106 may be pressedinto contact. The poly-based film may be held taut during the attaching.

In at least some embodiments, the attaching of the copper foil 102 tothe poly-based film 106 and the attaching of the metallic burrsuppressor 103 to the poly-based film are performed concurrently.

At operation 808, the copper foil and the poly-based film may beprocessed to remove any air bubbles between these layers. For example,in some embodiments, the copper foil and the poly-based film aresqueezed together by the roller to roll out any air bubbles. Similarly,the air bubbles between the metallic burr suppressor 103 and thepoly-based film may also be removed. When a machine of the typedescribed above with reference to FIG. 7 is used, the removal of the airbubbles between all three of these layers is performed concurrently.

While the discussion above generally described an embodiment in which apoly-based film acts as an intermediary to connect a metallic burrsuppressor to a copper foil, in other embodiments, the poly-based filmmay not be used and, instead, the metallic burr suppressor of the typedescribed above may be attached directly to a copper foil of the typedescribed above with an adhesive of the type described above. In suchembodiments, the adhesive may be permanently attached to the metallicburr suppressor and removably attached to the copper foil.

The various embodiments presented above are merely examples. Variationsof the innovations described herein will be apparent to persons ofordinary skill in the art, such variations being within the intendedscope of the present application. In particular, features from one ormore of the above-described example embodiments may be selected tocreate alternative example embodiments including a sub-combination offeatures which may not be explicitly described above. In addition,features from one or more of the above-described example embodiments maybe selected and combined to create alternative example embodimentsincluding a combination of features which may not be explicitlydescribed above. Features suitable for such combinations andsub-combinations would be readily apparent to persons skilled in the artupon review of the present application as a whole. The subject matterdescribed herein and in the recited claims intends to cover and embraceall suitable changes in technology.

What is claimed is:
 1. A burr-suppressing copper foil comprising: apoly-based film having an adhesive on a first side and an adhesive on asecond side; a copper foil contacting the adhesive at the first side ofthe poly-based film to removably couple the poly-based film to thecopper foil; and a metallic burr suppressor contacting the adhesive onthe second side to removably couple the poly-based film to the metallicburr suppressor.
 2. The burr-suppressing copper foil of claim 1, whereinthe metallic burr suppressor is a non-ferrous metal.
 3. Theburr-suppressing copper foil of claim 1, wherein the metallic burrsuppressor is a copper layer.
 4. The burr-suppressing copper foil ofclaim 3, wherein the copper metallic burr suppressor is between 17 and70 microns thick.
 5. The burr-suppressing copper foil of claim 1,wherein the metallic burr suppressor is an aluminum layer.
 6. Theburr-suppressing copper foil of claim 5, wherein the aluminum metallicburr suppressor is between 150 to 250 microns thick.
 7. Theburr-suppressing copper foil of claim 1, wherein the poly-based film isa polyethylene terephthalate (PET) film.
 8. The burr-suppressing copperfoil of claim 1, wherein the adhesive is a low-tack adhesive that allowsthe copper foil to be easily removed from the poly-based film and theadhesive.
 9. The burr-suppressing copper foil of claim 8, wherein theadhesive has a tack strength less than or equal to 6 grams per 25millimeter width.
 10. The burr-suppressing copper foil of claim 8,wherein the adhesive is permanently applied to the poly-based film. 11.The burr-suppressing copper foil of claim 1, wherein the adhesive isnon-silicone based.
 12. The burr-suppressing copper foil of claim 1,wherein the adhesive is an acrylic adhesive.
 13. The burr-suppressingcopper foil of claim 1, wherein the poly-based film is one that does notdeteriorate under heating at temperatures of one hundred and eightydegrees Celsius (180° C.).
 14. The burr-suppressing copper foil of claim1, wherein the adhesive is uniform across a surface of the poly-basedfilm.
 15. A method of manufacturing a burr-suppressing copper foil, themethod comprising: providing a copper foil, a metallic burr suppressor,and a poly-based film, the poly-based film having an adhesive applied toopposing sides of the poly-based film; attaching the copper foil to thepoly-based film at a first side of the poly-based film using theadhesive; and attaching the metallic burr suppressor at a second side ofthe poly-based film using the adhesive.
 16. The method of claim 15,further comprising: cleaning the poly-based film prior to the attaching.17. The method of claim 16, wherein cleaning comprises passing thepoly-based film over an adhesive take-up roller, the adhesive take-uproller having a tack for removing debris.
 18. The method of claim 15,further comprising: cleaning the copper foil prior to the attaching. 19.The method of claim 15, further comprising: cleaning the metallic burrsuppressor prior to the attaching.
 20. The method of claim 15, furthercomprising: removing any air bubbles between the copper foil and thepoly-based film; and removing any air bubbles between the metallic burrsuppressor and the poly-based film.